Ancient oyster shells provide historical information

An interdisciplinary team of scientists studying thousands of oyster shells along the Georgia coast, some up to 4,500 years old, have published new ideas on how Native Americans maintained oyster harvests for thousands of years, observations that can lead to best oyster reef management practices today. .

Their study, led by University of Georgia archaeologist Victor Thompson, was published July 10 in the journal. Scientific advances.

The new research argues that understanding the long-term stability of coastal ecosystems requires documenting the past and present conditions of those environments, as well as considering their future. The findings highlight a remarkable stability of oyster reefs before the 20th century and have implications for oyster reef restoration by serving as a guide for selecting suitable oyster restoration sites in the future.

Seafood, like oysters, has long been a staple food for human populations around the world, including Native American communities along the southeastern coast of the United States. The eastern oyster Crassostrea virginica is a species frequently studied by marine biologists and ecologists due to the central role the species plays in coastal ecosystems.

Oyster reefs are a key species that provides critical habitats for other estuarine organisms. However, oyster populations have declined dramatically worldwide in the past 100 years due to overexploitation, climate change and habitat degradation.

“Oyster reefs were an integral part of the Native American landscape and our study shows that their sustainability over long periods of time was likely due to the sophisticated cultural systems that govern harvesting practices,” said Thompson, professor of anthropology at the Franklin College of Arts. and Sciences and director of the UGA Archeology Laboratory.

According to Thompson, the previous models used by archaeologists have not adequately explained the role that indigenous peoples had not only in the maintenance of ecosystems, but also in the improvement of biodiversity.

“Our research shows that the harvest was probably done with the goal of achieving sustainability by Native American communities,” he said. “Working here along the Georgia coast, together with colleagues working in the Pacific and the Amazon, indicates that indigenous peoples had a wealth of traditional ecological knowledge about these landscapes and actively managed them for thousands of years” .

Changes in the size and abundance of oyster shells are widely used to examine the pressures of the human population and the health of oyster reefs. The researchers measured almost 40,000 oyster shells from 15 archaeological sites from the Late Archaic period (4500-3500 years before the present) to Mississippi (1150-370 years BP) located along the coast of the South Atlantic of the United States to provide a long-term record of practical oysters at harvest and to document the abundance and size of oysters over time.

The new findings show an increase in the size of oysters over time and a non-random pattern in their distributions across archaeological sites along the coast that the authors believe is related to the variable environmental conditions that are occurring. found in different areas.

When the researchers compared their work to maps of 19th-century oyster reef distributions, they found that the two were highly correlated. All data on oyster size and reef size suggested that there was considerable stability in oyster productivity over time, even if some reefs were not as productive as others. However, this overall productivity changed in the early 20th century when industrial oyster canning devastated the reefs, leaving only a small percentage of the reefs viable today.

“This work, which was partially supported by Georgia’s long-term ecological research project for coastal ecosystems, demonstrates the importance of understanding the role humans play in shaping the landscape, and that is something that is not always appreciated. in ecological studies, “said Merryl Alber, professor and director of the UGA Marine Institute on Sapelo Island, an excavation site for this study.